A GROUND WATER LEVEL ESTIMATION MODEL WITH SIMPLIFIED RAINFALL INFILTRATION AND SEEPAGE PROCESS IN SURFACE SOIL LAYER

Abstract

 Japan is vulnerable to landslide disasters caused by heavy rainfall. The most common type of landslide disasters is slope failure. In order to mitigate slope failure disasters, a real-time forecasting system using short-term rainfall prediction information is needed. One of the key factors of slope failure is the ground water level. Therefore it is important to determine the ground water level in the surface soil layer in order to carry out a risk assessment. The most important of risk assessment is to evaluate the potential of slope failure quickly, in order to provide advance warning and enable local residence to be evacuated in good time. In this respect, an accurate analysis of the data, together with a simulation of the behaviour of ground water in the surface soil layer, will help to assess the potential for slope failure.
 The ground water level estimation model, using the relationship between the ground water level and surface soil layer (H/D-S_r) is proposed as a model which can be analyzed in a short period of time. In this model, both rainfall infiltration and the seepage processe s are simplified by using this relationship. In this paper, the authors propose to modify this model in order to improve estimation accuracy. In addition, field reliability of the proposal model is verified by comparing it with the results of the saturated - unsaturated flow analysis (FEM). As a result, its effectiveness is confirmed.